Process for obtaining adhesive coatings of copper upon iron and steel.



UNITED STATES PATENT OFFICE.

SHERAED OSBORN COWPER-COLES, OF WESTMINSTER, LONDON, ENGLAND.

PROCESS FOR OBTAINING ADHESIVE COATINGS OF COPPER UPON IRON AND STEEL.

No Drawing.

To all whom it may concern Be it known that I, SHERARD 'OsBoRN CowrEn-CoLEs, a subject of the King of Great Britain, residing at 1 and 2 Old Pye street, lVestminster, London, England, have invented a new and useful Improved Process for Obtaining Adhesive Coatings of Copper upon Iron and Steel; and I do hereby declare that the following is a full, clear, and exact description of the invention, which will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to an improved process for obtaining adhesive deposits of copper upon iron and steel.

According to my. invention I obtain an adhesive deposit of copper upon iron or steel by first rendering the surface passive say by subjecting the metal, after it has been cleansed, to the action of concentrated nitric acid, chromic acid, or potassium hydroxid or by making it the anode in a suitable electrolyte or by any other wellknown method, the metal so treated being then at once removed to an electro copper depositing tank to receive the desired coating of copper. I have found that copper thus deposited upon the surface of iron or steel, rendered passive by the preliminary action of nitric acid, is so adherent that it cannot be removed by ordinary mechanical means, the two metals being entirely welded together.

Referring to my use of the term passive it may be stated, that passivity is a phenomenon occurring among certain metals that possess the power of assuming a difierent state, after certain chemical treatment, their anodic properties being altered.

In carrying out my invention I advantageously proceed as follows :'The iron or steel to be coated is first thoroughly cleansed by pickling or sand blasting, after which it is washed in running water and dipped in a concentrated solution of nitric acid. As soon as the evolution of gas bubbles on the surface of the iron or steel ceases, which usually is in about half-a-minute, the metal is removed from the acid and washed preferably in running water. It is then trans- Specification of Letters Patent.

ferred to an electro copper depositing tank the anode and cathode of which have been already connected up in the electric circuit prioT to the introduction of the passive metal, so that the latter is immediately coated with copper on its immersion.

The electrolyte in the copper depositing tank may be composed as follows: 10 ounces of cyanid of potassium are dissolved in 80 ounces of water, the solution being then heated to nearly boiling point and 6 ounces of copper sulfite being added gradually under constant stirring. The temperature is then raised to boiling point, and the solution is allowed to cool, after which it is filtered and 80 ounces of water added. Or the electrolyte may be composed of potassium cyanid having copper carbonate dissolved in it, sodium bisulfite being added to the solution. The solution thus prepared is used at a temperature of about 60 C. with a. current density of about 3 amperes per Square foot of cathode surface. When the steel 01 iron has received a coating of copper in the depositing tank it is removed, thoroughly washed, referably with hot water, and immediately transferred to a copper sulfate depositing tank'in which it is allowed to remain until the copper coating has obtained the desired thickness.

By my process I am'able to obtain deposits of copper upon iron and steel which are so adhesive that they cannot be sepathe said iron or steel passive and then depositing the coating of copper thereon.

2. A process for obtaining an adhesive coating of copper upon iron or steel, which consists in first cleansing the metal to becoated, then rendering the surface of said metal passive and then depositing the coating of copper thereon.

3. A process for obtaining an adhesive Patented Sept. 19, 1916.

Application filed August 24, 1914. Serial No. 858,336.

coating of copper upon iron or steel which trolytically depositing copper upon the consists in first rendering the surface of metal, from anacid, copper contalning sothe metal to be coated passive, by immerlution.

,7 sion in a concentrated solution of nitric SHERARD OSBORN OOWPER-COLES.

5 acid, then electrolytically depositing cop- \Vitnesses: per upon the metal, from an alkaline, cop- JOHN E. BoUsFIELD,

per containing solution, and then elec- A. ALBUTT. 

